(Originally wrote by RLR)--------------------------------------------------------------------------------

The heart has a natural pacemaker called the sinoatrial node among several less distinct and similar pacers, whose steady rythmic signals can be affected by which nerve? You guessed it; The VAGUS nerve.

Among its many duties, the vagus nerve helps transfer signals within the parasympathetic nervous system to the brain to regulate the heart in addition to other functions taking place and is doing its job right now in each and every one of us. Think of the nervous system as a two-way street, one being the sympathetic nervous system that sort of represents stepping on the gas peddle, and the parasympathetic nervous system that is analgous to stepping on the brakes so to speak. When your heart races, think sympathetic nervous system and when it slows down, think of the parasympathetic system. See?

So for our purposes, we want to focus mainly on the parasympathetic nervous system, particularly with respect to the 10th cranial nerve otherwise known as the vagus nerve.

The variability of your heart rate during inspiration and expiration of your lungs is an effect of the vagus nerve. We've all noticed that when we take a breath in, our heart tends to beat just a little faster and when we breath out, a little slower. It's an entirely normal bodily function and is connected to the need by the body's system to respond to the environment. It's a very simple example of the sympathetic and parasympathetic nervous system working in concert with other physiological processes. But sometimes extra signals along the vagus nerve due to over-stimulation can directly affect the organs involved in a way that was not normally intended, namely the heart, and cause extra activity to occur like palpitations. It merely represents a misguided nerve impulse coming from the nervous system and not a message from the heart that something is wrong in this case. Does that make sense? It's sort of like an involuntary muscle twitch. Nothing more.

Now that we kind of have a little medical background under our belts, let's take one of the complaints by many of you regarding the proximity or untimely appearance of palpitations and indigestion. Remember that we said the vagus nerve is linked to both the tummy, the throat and the heart. Let's assume that we've eaten meal and it's caused us to experience some gastrointestinal discomfort, or in other words, gas. The irregular presence and activity by your tummy and intestines stimulates, more appropriately irritates, the vagus nerve which sends a rather inappropriate signal back along the pathway to guess where? That's right! The heart. Move to the head of the class. The heart is busy pacing away regularly and is relatively unconcerned with all the food you poured into your tummy, when all of a sudden in comes a signal from the vagus nerve because it has been inappropriately stimulated and tells the heart to beat. Well, just like our bad date example, the signal to beat is rather untimely and awkward but the heart has to accept it and respond. The result is extra beats that make the heart feel like it is stumbling. The degree to which it stumbles oftentimes depends upon the extent to which the vagus nerve is irritated and the relative state of indigestion present as the causitive agent.

There is most often no pain assoicated with this occurrence because it is not the result of a lack of blood or oxygen that creates the palpatation, but rather just a simple additional electrical impulse or series of impulses. Pericardial pain, or pain adjacent to the heart, can sometimes accompany palpitations or exist exclusive of any arrythmia, but is not necessarily considered pathologic or harmful to us. Remember that we're dealing with inappropriate electrical impulses and typically more nerves than just the Vagus nerve are affected and can respond inappropriately, causing a jabbing or shooting pain than many describe as a "catch" in their chest. We'll talk more about chest pain in a bit.